Process of treating fresh fruit



Patented July 17, 1934 1,967,074

UNITED STATES PATENT OFFICE.

PROCESS OF TREATING FRESH FRUIT John (J. Baker, Montclair, N. J.

No Drawing. Application October 14, 1931, Serial No. 568,873

7 Claims. (C1. 99-1) This invention relates to processes of treating method of application of the sterilizing gas enfresh fruit to prevent decay. 'In the commercial tails some additional operations over the present production, storage and marketing of fruit or methods of handling the fruit, so that it is much the like, great losses are caused by decay promore convenient to expose the fruit either in the duced by moulds or other similar organisms. containers in which it is collected and delivered 60 Such organisms enter usually through injuries to the packing plant, or in the finished package to-the skin of the fruit. Numerous methods of ready for shipment. sterilizing the fruit, or at least inhibiting the The treatment of the fruit after it has been growth of such organisms, have been resorted to wrapped in paper or wrapped and packed in 10 with more or less success. Hypochlorite or borax boxes or crates has the advantage that the paper solutions, sulphur dioxide and alkaline treatments wrapping prevents the re-inoculation of injuries have all been used for this purpose. by mould spores after the sterilization treatment.

Solutions have the disadvantage that they wet The paper is sufiiciently pervious to the treating mould spores or the like with difiiculty, and unless gas to make the sterilizing treatment effective wetting occurs the treating reagent cannot act. but is substantially impervious to mould spores 70 Further, several, if not all, prior reagents are or other decay producing organisms. The sterispecific in their action and do not destroy all lization after wrapping or after wrapping and yp of decay Producing Organisms i packing also eliminates the possibility of the skin y- For mp I i ff c iv a ains or fruit being injured and such injured parts green mould, but has little action in the case of becoming inoculated with mould spores or the 75 blue mould or bla k s em r Th is p i lly like, intermediate the time at which sterilizaserious sin e u m u d r pidly p a s'th ushtion treatment is given and the time that the ou an e t p fruit is packed in crates ready for shipment.

Ihave discovered that sterilization or inhibition hi i of importance in view of the fact that f rowth of or ni m on fr i can e b in d the treatment with nitrogen trichloride does not so by the use Of nitrogen trichloride in the form give complete immunity against subsequent in- Of l highly d d w h a relatively inert oculation. There is some immunity, however, as gas, such as air. tests have shown that the treatment renders the Amixture of air and nitrogen trichloride, when injured portions of the skin much less readily appli d o the fruit in defi ite o c t at on susceptible to subsequent inoculation than porand for a suitable length of time, produces retions injured after such treatment. sults which are superior to those obtained by While the gaseous nitrogen trichloride has difother methods or other reagents. As the reagent ficulty in reaching the parts of the fruit pressed is in gaseous or vapor form, it will readily peneagainst each other or the walls of the crate, it

35 trate and act upon the spores, moulds, and other is also diflicult, for the same reasons, for air organisms in the injured and on the other parts to reach such parts, and without air moulds have of the skin of the fruit. Further, the reagent diificulty in growing. Hence, the incompleteness nitrogen trichloride is effective in killing not only of sterilization is not as serious as might be exall kinds of moulds, but also their spores. This pected.

40 is particularly true in the case of citrus fruits. The fruit may be treated with wax or the like e gaseous mixture When applied in the D p to restrict shrinkage by evaporation of water beeoncen r i t0 Citrus fruits does not injure the fore treatment with nitrogen trichloride without Skin exterior Surface of the fruit but destroys destroying the efiectiveness of such treatment. any organisms included in those spots where Gaseous sterilizing agents are very efie tiv at 45 injuries occurred f thereby lmproves the the time of application-more so than solutions keepmg quahty of the of solid substances like borax. However, being Numerous m t g i fi g g gaseous, their effects are more temporary than frult can be utmzed' emos o solutions which, on evaporation of the solvent, so far as completeness of sterilization is conleave behind the growth inhibiting or destroying 5o cerned, is that in which the fruit is in motion d b1 t t or is turned during the period of exposure so Sohds dissolved therem- A 8 ma ment by that all portions of the fruit are exposed to the the two types of therefore, highly fgas. This can be readily accomplished by p iective. The fruit may be first treated with a ing the fruit through a long tube with a counter r x 1 Si r Solution, th n dried, wrapped.

55 current of the gas in the other direction. This and finally Subjected to the action of nitrogen trichloride to complete the destruction of organisms accomplished in part by the borax.

One highly satisfactory method by which the invention may be carried into effect is to wrap the fruit, such as oranges, in paper, pack them in standard cases, and then expose the cases to air carrying about 0.05 gram of nitrogen trichloride per cubic foot for about one hour at ordinary room temperature. Similar results may be obtained by exposing the oranges to a lower concentration for a longer time, or to a higher concentration for a shorter time. Usually, however, the concentration of nitrogen trichloride will be between 0.01 and 0.5 gram per cubic foot of air. Also, the conditions of treatment may somewhat depend upon the temperature, low temperatures requiring either higher concentrations or slightly longer time. The effectiveness of this method of treating oranges has been demonstrated by purposely injuring the fruit and inoculating it with the ordinary organisms which appear in mould, treating a portion of the inoculated fruit with air carrying nitrogen trichloride, and comparing the keeping quality of the treated and untreated portions. It was found that when the untreated portion had deteriorated to the extent that every fruit exhibited mould decay, in the treated portion somewhere between and of the fruit was still good. In the above demonstration the fruit was wrapped and crated so that the gas did not have equal opportunity to reach all parts of the skin of the fruit. In other demonstrations, where the fruit was treated in a tube or other means adapted to keep the fruit in motion during treatment a still higher percentage was found to be in good condition.

There are numerous methods of making nitrogen trichloride. The simplest method is the one disclosed in my Patent No. 1,510,132. Other methods of making nitrogen trichloride are disclosed in my Patent No. 1,367,530. The gas as produced in these methods is suitable for use in my present process of sterilization, even though it may contain small amounts of chlorine, with the exception that the amount of air with which the gas is diluted should be carefully regulated and known.

It is undesirable to treat citrus fruits with excessive concentrations of the gas for a long time as this tends to injure or destroy the protective surface of the fruit and increase the shrinkage from evaporation. Also, the various citrus fruits differ somewhat in their resistance to the gas. Lemons in general are more sensitive than are oranges and should be treated accordingly.

My method oftreatment is not limited to citrus fruits, but is to be applied to any fruit or vegetable which is ordinarily subject to decay and which will not be injured by application of the gas, and the term fruit" as used in the specification and claims is to be given this broad interpretation.

It will also be understood that the term "sterilization is not to be interpreted in its strictest scientific sense, but is to be understood as including all treatments which are markedly sterilizing from a practical commrnercial point of view. Further, the term sterilization is intended to include not merely destruction of life, but also inhibition of the growth and reproduction of mould and other organisms.

What is claimed is:

1. The process of treating fresh fruit to prevent decay, comprising subjecting the fruit to the action of nitrogen trichloride gas highly diluted with a relatively inert gas in a concentration and for a length of time effective to prevent decay but insuflicient to injure the protective surface of the fruit.

2. The process of treating fresh fruit to prevent decay, comprising subjecting the fruit to the action of air carrying from 0.01 to 0.5 gram of nitrogen trichloride per cubic foot for a sufiicient length of time to prevent decay but insuflicient to injure the protective suriace of the fruit.

3. The process of treating fresh fruit to prevent decay, comprising wrapping the fruit in paper, and subsequently subjecting the wrapped fruit to the action of a gas containing, in amounts effective to prevent decay but insuflicient to injure the protective surface of the fruit, nitrogen trichloride in gaseous form.

4. The process of treating fresh citrus fruit to prevent decay, comprising wrapping the fruit in paper, and subsequently subjecting the wrapped fruit to the action of a gas containing, in amounts effective to prevent decay but insufiicient to injure the protective surface of the fruit, nitrogen trichloride in gaseous form.

5. The process of treating fresh fruit to prevent decay, comprising exposing the fruit in transport containers to the action of a gas containing, in amounts effective to prevent decay but insufficient to injure the protective surface of the fruit, nitrogen trichloride in gaseous form.

6. The process of treating fresh fruit to prevent 1 decay, comprising exposing the fruit in the containers in which it is collected and delivered to the packing plant to the action of a gas containing, in amounts effective to prevent decay but insufficient to injure the protective surface of the fruit, nitrogen trichloride in gaseous form. v

7. The process of treating fresh fruit to prevent decay, comprising exposing the fruit in the finished package ready for shipment to the action of a gas containing, in amounts effective to prevent decay but insufficient to injure the protective surface of the fruit, nitrogen trichloride in gaseous form.

JOHN C. BAKER. 

